Antagonism by CGS 8216 and Ro 15-1788, benzodiazepines antagonists, of the action of chlordiazepoxide on a timing behavior in rats.

Rats were trained to respond under a differential reinforcement of low rate (DRL) schedule of reinforcement. Pretreatment with relatively low doses of chlordiazepoxide (1-10 mg/kg) produced increases in total DRL responses and decreases in the numbers of reinforced responses. Chlordiazepoxide produced a shift in the interresponse time (IRT) distribution of DRL responses. Low doses of chlordiazepoxide shifted the IRT distribution of DRL responses. Low doses of chlordiazepoxide shifted the IRT distribution from the reinforced to the non-reinforced bins. In addition there was marked increase in the number of responses that occurred in the earliest IRT bin (0-3.75 sec). The highest dose of chlordiazepoxide (32 mg/kg) produced a decrease in total DRL responses and resulted in an even IRT distribution of responses. Both CGS 8216 and Ro 15-1788 had minimal effect on DRL responding when given alone. Ro 15-1788 had no effect at either 10 or 32 mg/kg, while CGS 8216 produced decreases in DRL responding at 32 and 100 mg/kg. Both Ro 15-1788 and CGS 8216 antagonized the effects of high and low chlordiazepoxide doses on total DRL responding and on the IRT distribution of responding.